Fluid pressure brake system



Feb. 1, 1938. w. o v 2,106,758

FLUID PRESSURE BRAKE SYSTEM Filed Feb. 28, 1954 5 sheets sheet 1 4 INVENTOR. Wax .400: FOL/V55 7 BY W, a 7W dug/"M ATTORNEYS a w. F. OLIVER FLUID PRESSURE BRAKE SYSTEM Feb. 1, 1938.

Filed Feb. 28, 1954 3 Sheets-Sheet 2 as so INVENTOR. l l flLL we: f OLA/6 ATTORNEYS Feb. 1, 1938. w, OLIVER 2,106,758 I FLUID PRESSURE BRAKE SYSTEM Filed Feb. 28, 1934 3 Sheets-Sheet 5 N WI INVENTOR.

4w WQLLQCf/f 04/1 56 TTORNEYS Patented Fel a. 1, 1938 UNITED STATES FLUID PRESSURE BRAKE SYSTEM Wallace F. Oliver, Detroit, Micln, assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application February 28, 1934, Serial No. 713,259

10 Claims. (Cl. 188-152) This invention relates to fluid pressure brake systems and more particularly to devices for creating an initial pressure in the system.

It has been found that in the operation of fluid brake systems a considerable movement of the brake pedal lever is necessary in order to take up the clearance between the friction elements and the drum of the-brake, and lost motion due to play between the mechanically interconnected parts of the mechanism. The present invention aims to overcome these objections.

An object of the invention is to provide means for automatically taking up slack in a. brake system and for moving the friction elements into engagement with the drums.

Another object of the invention is to provide means automatically operated to introduce an initial pressure in the system upon the initial movement of the foot pedal lever from its normal position. r

A further object of the invention is to provide a fluid brake system including means automatically operated by power supplied from the prime mover of the vehicle and effective to introduce an initial pressure in the system upon the initial movement of the foot pedal lever tending to apply the brakes.

Other objects and advantages of the invention will appear from the following description taken in conjunction with the accompanying drawings in which,

Figure 1 is a diagrammatical illustration of a motor vehicle equipped with a hydraulic brake system embodying the invention;

Figure 2 is an enlarged sectional view of one of the valves included in the system;

Figure 3 is an enlarged sectional view of a duplex valve included in the system.

Figure 4 is a sectional view substantially on line 44, Figure 3;

Figure 5 is a longitudinal sectional view of a primary compression device included in the system; and

Figure 6 is a longitudinal sectional view of a secondary compression device also included in the system.

Referring to the drawings for more specific details of the invention, I0 represents the body of a motor vehicle including floor boards l2 and a foot board 14. A cross-member 16 of a chassis frame positioned beneath the body has suitably secured thereto a primary compression device l8 including a cylinder 20 provided with inlet ports 22 and 24 and an outlet or discharge port 26.

A reciprocable piston 28 in the cylinder is retained against displacement by a washer 30 seated on a. ring 32 fitted in a circumferential groove in the wall of the cylinder. This piston has a body portion reduced in cross-section providing, in conjunction with the wall of the cylin- 5 der 20, a chamber 34 communicating with the port 24, and the head of-the cylinder has a plurality of openings 36 providing communications between the chamber 34 and that portion of the cylinder chamber forward of the piston, and suit- 0 ably secured on the head of the piston is a collapsible leak-proof cup 38. The skirt of the pis ton has a circumferential groove in which is fitted a leak-proof washer 40, and formed in the back of the piston is a recess 42. 15

A bracket 44 on the cross-member l6 has pivoted thereto a foot pedal lever 46 extending through the foot board l4 and held in its normal position by a retractor spring 41. This lever has an arm 48 to which is pivotally connected 9. 20

thrust pin 50, the free end of which is received by the recess 42 in the back of the piston, and a dust shield or boot 52 is connected between the thrust pin and the open end of the cylinder.

The outlet or discharge port 26 of the cylinder 5 20 communicates with a conduit 54 having branch conduits 56 and 58 communicating respectively with conduits 60 and 62, the respective ends of which are connected to motor cylinders 64. These cylinders may be of any conventional 30 type and each of these cylinders is connected be-- tween the respective ends of frictional elements 66 and 68 adaptable for cooperation with a retatable drum ill which may be suitably secured to a wheel, not shown, and connected between the separable ends of the friction elements are retractor springs 12 for returning and retaining the friction elements in retracted position.

The inlet ports 22 and 24 of the cylinder 20 are connected by conduits I4 to a duplex valve I6 suitably secured on the foot board H! in the path. of the foot pedal lever 46. This valve includes a chamber divided by a diaphragm including a valve seat 18 into two compartments 8!! and 82. The compartment 80 has a port 84 communicating with the conduit 14, and the compartment 82 has a port 86, the purpose of which will hereinafter appear.

The compartment 80 has therein a ball valve 88 urged against its seat 18 by a coil spring I0, and the compartment 82 has threaded therein a cup 92 in which is mounted a plunger 94 for actuating the valve 88. As shown, the plunger 94 has thereon a leak-proof cup 96, a sleeve or collar 98,

and a coil spring I00 interposed between the collar and the valve seat.

Arranged in parallel relation to the compartments 00 and 02 is a valve chamber I02 having a port I04 providing a communication between the compartment 00 and the chamber I02 and a port I00, the purpose of which will hereinafter appear. The chamber I02 has therein a slide valve I00 having an axial passage H0, and spaced circumferential flanges between which is fitted a leak-proof cup II2. This valve is urged to seat on a shoulder H4 in the chamber by a spring H6 interposed between the valve and the plug II8 threaded in one end of the chamber, and

threaded in the other end of the chamber is a plug I 20 having mounted therein a plunger I22 provided with spaced circumferential flanges between which is fltted a leak-proof cup I24, and a frustro-conical head adapted to control the passage H0 in the slide valve I00. The valve I00 normally prevents communication between the cylinders 20 and, I34.

- A secondary compression device I20 includes a reservoir I20 connected by a conduit I30 to the port 00 of the duplex valve 10. This reservoir has a filling opening closed as by a plug I32 which may be provided with a vent, and formed in the bottom of the reservoir is a cylinder I34 having a port I30 adjacent one end thereof providing a communication between the reservoir and the cylinder, and a port I30 adjacent its other end .D rt I40, the purpose of which will hereinafter appear. A reciprocable piston I50 in the cylinder I40 has a sealing ring I52 and a sleeve or 001- lar I54. A rod I50 is suitably secured in the sleeve or collar. This rod extends through a bushing I50 secured in the head of the cylinder I40, and hasthereon a collar I00 held against displacement bya nut I02 secured in position by a lock nut I04, and sleeved on the rod between the cylinder I40 and the collar I00 is a coil spring I 00 for actuating the piston. Y

A rod I00, suitably secured in the sleeve I54 as by a thimble I10 threaded in the sleeve, extends through a packing box I12 into the cylinders I34. The packing box is threaded in the open end of thecylinder I 34, and has therein a leak-proof cup I14 held against displacement by a collar I10 clamped between the packing box and the wall of the cylinder.

A piston I10 in the cylinder I34 is suitably secured to the rod I00. This piston has a plurality of openings I00 providing communications between the respective ends of the cylinder, and a leak-proof cup I02 on the piston controls the opening; As shown, the piston I10 has a concentric portion I04 providing a seat for the cup on the retracted 'stroke of the piston, and the portion I 04 is slotted to provide passages I00, and a concentric pin I00 on the piston extends through an axial opening in the cup with substantial clearance as at I90, and a disk I92 secured on the pin provides a seat for the cup during the compression stroke of the piston. passage I00 and the clearance I90 provide for the circulation of fluid past the cup I02 when the piston moves to its retracted position.

A valve I94 positioned on the foot board H in the path of the foot pedal lever 46 is connected by a conduit I90 to the port I 40 in the cylinder I40 and by a conduit I00 to the intake manifold 200 of the prime mover. This valve includes a valve chamber 202 having therein a valve seat 204 and a valve 200 urged against the seat by a coil spring 200. The stem of the valve 200 extends through a suitable packing box 2", and an adjusting bolt 2I2 threaded in the end of the stem is arranged for engagement with the foot pedal lever when this lever is in retracted position.

Assuming that the system is filled with suitable fluid, upon the initial movement of the foot pedal lever 40 to apply the brakes, the valve 200 is released and actuated by the spring 200 to closethe communication between the cylinder I40 and cessive operation by the foot pedal lever so that communication between the reservoir I20 and the cylinder 20 is closed prior to establishing communication between the cylinder I34 and the cylinder 20. The successive operation of the valves 00 and I00 is accomplished by making their respective plungers 94 and I22 of. such relative lengths that they are engaged and disengaged by the pedal 40 in the proper sequence. On entering the duplex valve 10, the fluid passes through the slide valve I00 therein, and passage I04, through compartment and port 04 and conduit 14 connected thereto, through the ports 22 and 24 into cylinder 20,.and thence through conduit 54 and branch conduits 50, 50, 00 and 02 into the motor cylinders 04, resultingin actuation of these motors to spread the friction elements 00 and 00 into engagement with the drums 10 against the resistance of the retractor springs 12.

During this initial movement, the piston 20 has traveled sumciently on its compression stroke to cover the port 22, and further movement of the piston 20 discharges fluid from the cylinder 20 through port 20, the conduit 50' connected thereto and branch conduits, 50, 50, 00 and 02 into the motor cylinders, resulting in further energizing these cylinders and thereby spreading .the fric- ,tion elements 00 and 00 into engagement with the drum 10 to effectively resist rotation of the drums.

Upon release of .the foot pedal lever 40 it is returned to its retracted position by a conventional retractor spring, and as this lever returns to its retracted position it engages the adjustable bolt is transmitted to the piston.l10 to move the piston I10 on its retracted stroke.

As the piston I10 moves on its retracted stroke, fluid from the reserv'oir I20 passes the cup I02 and circulates through the passages I00 in the piston and into the cylinder I 34 forward of the piston to completely fill that portion of the system including I40. This causes its retracted position by fluid returning from the motor cylinders 64 due to pressure imposed by the retractor springs 12 connected between the friction elements 68 and 88.

Upon complete return of the piston 28 to its retracted position, the port 22 is uncovered,

whereupon further pressure in the cylinder 20 causes the cup 88 to return to static condition, and any further fluid returned to the cylinder 20 from the motor cylinder .88 is discharged from the cylinder 28 through the port 22 and conduit 14, valve 16 and conduit I30, into the reservoir I28.

Although this invention has been described in connection with certain specific embodiments, the principlm involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid pressure operated brake system for a motor vehicle havingan internal combustion engine, comprising a reservoir for supplying fluid to the system, a primary means for producing pressure, a secondary means for producing pressure, means for actuating the secondary means including means connected to the intake manifold of the engine, a valve for controlling the actuating means, means for circulating fluid from the reservoir through the secondary means and back to the reservoir, a valve connected in the circulating means, and means for actuating the primary means including means for operating the valves successively.

2. A fluid pressure operated system comprising a primary means for producing pressure, a secondary means for producing pressure, a reservoir for supplying fluid to both pressure producing means, a valve connected between the primary and secondary pressure producing means and the reservoir operable to provide for circulation of fluid from the reservoir through the secondary pressure producing means and back to the reservoir.

3. A fluid pressure operated brake system for a motor vehicle having an internal combustion engine, comprising a primary means for producing pressure, a motor cylinder connected thereto, a brake element operated by the motor cylinder, a secondary means for producing pressure, a reservoir for supplying fluid to both pressure producing means, a conduit connected between the primary and secondary pressure producing means, a valve connected in the conduit, a conduit connecting the valve to the reservoir, a vacuum chamber, a spring-pressed piston therein connected to the secondary means, a conduit connecting the vacuum chamber to the intake manifold of the engine, a valve connected in the conduit, and means for actuating the primary means including means for actuating the valves.

4. A fluid pressure operated brake system for a motor vehicle having an internal combustion engine, comprising a primary means for producing pressure, motor cylinders connected thereto, brake elements operated thereby, a secondary means for producing pressure, a reservoir for supplying fluid to both pressure producing means, a valve connected between the primary means and the secondary means and between the primary means and the reservoir, a vacuum chamber, a spring actuated piston in the vacuum chamber, a valve connected between the vacuum chamber and the intake manifold of the engine, and an actuator for the primary means controlling the valves.

5. A fluid pressure operated system comprising a compression device including a reservoir, a cylinder having a port providing a communication between the reservoir and the cylinder and a discharge port, a reciprocable piston in the cylinder, a vacuum chamber, a piston reciprocable therein connected to the piston in the cylinder and having a rod extending through the head of the chamber, a collar on the rod, and a compression spring on the rod between the collar and the head of the chamber.

6. A fluid pressure operated system compris-.

ing a compression device including a reservoir, a cylinder in the bottom thereof having a port providing a communication between the reservoir and the cylinder and a discharge port, a piston reciprocable in the cylinder having openings in its head for circulation of fluid through the piston, a leak-proof cup on the piston for controlling the flow of fluid through the piston, a vacuum chamber arranged concentrically to the cylinder, a piston reciprocable therein, a rod connecting the piston in the chamber to the piston in the cylinder, a rod for .the piston in-the chamber extending through the head of the chamber,

a collar on the rod, and a compression spring between the collar and the head of the chamber.

7. A fluid operated system comprising a compression device including a reservoir, a piston in the bottom thereof having a port providing a communication between the reservoir and the cylinder and a discharge port, a stufling box secured in the open end of the cylinder, a piston reciprocable therein having openings in its head for circulation of fluid through the piston, a leak-proof cup on the piston for controlling the flow of fluid through the piston, a rod for the piston extending through the stufflng box, a vacuum chamber arranged concentrically to the piston, a piston reciprocable in the chamber, a memberconnecting the piston to the rod for the piston in the cylinder, a rod attached to the piston in the chamber extending through the head of the chamber, a collar thereon, and a compression pressure. 1

9. A fluid operated brake system comprising a primary-means for producing pressure, a secondary means for producing pressure, a separate source of force for actuating each means, a reservoir for supplying fluid to both pressure producing means, and a valve mechanism connected in-the system operated to close the communication between the reservoir and the primary means and to establish communication, between the.

primary and secondary pressure producing means.

10. Afluid operated brake system comprising a primary means for producing pressure, a secondary means for producing pressure, a. reservoir,-

supplying fluid to both pressure producing means, motor cylinders connected to the primary means.

brake elements operated thereby, an actuator for ected in: 

